Substrate containers are used in the semiconductor processing industry for storing and transporting semiconductor wafers, flat panel substrates, and film frames. Examples of containers that are used in the semiconductor processing industry are FOUPs (front opening unified pods), FOSBs (front opening shipping box), and SMIF (standardized mechanical interface) pods. Such containers generally have an enclosure with an open bottom or side that is sealingly closed by a door. The doors often have an interior compartment with a latch mechanism that is visible through a clear or transparent plastic door panel, which is usually formed of polycarbonate.
Processing of semiconductor wafers into finished electronic components typically requires many processing steps during which the wafers must be handled and processed. The wafers are very valuable, extremely delicate, and easily damaged by physical and electrical shocks. In addition, successful high-yield processing requires maximum cleanliness and freedom from particles or particulates and other contaminants. Because of this requirement, specialized containers or carriers have been developed for use during processing, handling, and transport of wafers. These containers protect the wafers from physical and electrical hazards and are sealable to protect the wafers from contaminants. Such wafer carriers or containers generally comprise an enclosure having a number of wafer holding shelves inside. One side of the container is open for access but can be enclosed by a door. The doors generally have a latch mechanism to securely retain and seal it in place. Normally, the latch mechanism is enclosed to protect it from damage and accidental actuation.
Although wafer enclosures are used in clean environments, undesirable contaminants can accumulate on and in the enclosure over time. Particulate contaminants are generated through frictional contact between parts of the enclosure and in the operation of loading and unloading wafers from the enclosure. Accordingly, an important characteristic for wafer containers is that they must be thoroughly cleanable to ensure that process cleanliness is maintained. Cleaning is generally accomplished with a liquid solution and the parts are dried afterward with compressed air or other gas.
Semiconductor wafer fabrication processes are often extremely sensitive to any contamination. Contaminants can be generated in various ways, e.g., by sliding contact of components, such as latching mechanism components, within the substrate container door. As substrate containers are used over time, they can generate and accumulate particulates. Over time, the particulate formation can result in visible smudging, smearing, and/or clouding of the transparent plastic door panels. While this presents an undesirable aesthetic result, such contaminants and particles or particulates also present the risk of entering the enclosure and contaminating the wafers.
Because the general problems discussed above have not been addressed by conventional wafer containers, there is a current need for a wafer container addressing the problems and deficiencies inherent with conventional designs.